Separation of hydrogen sulfide from natural gas

a technology of hydrogen sulfide and natural gas, which is applied in the direction of separation process, gaseous fuel, fuel, etc., can solve the problems of presenting its own problems, achieve low co2 solubility, improve the operation of sulfur recovery plant, and reduce the cost and energy

Inactive Publication Date: 2015-01-29
EXXON RES & ENG CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009]There is therefore a need for an alkanolamine absorbent system that can selectively absorb H2S from gas mixtures that also contain CO2 and that can be regenerated at high pressure and relatively low temperature while maintaining very low CO2 solubility. This can significantly reduce the cost and energy required for regeneration and recompression as well as improving operation of the sulfur recovery plant.

Problems solved by technology

This preference may, however, present its own problems in certain circumstances.
However, H2S / CO2 selectivity significantly reduces at high CO2 pressure presumably due to O-carbonation of hydroxyl groups:

Method used

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  • Separation of hydrogen sulfide from natural gas
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  • Separation of hydrogen sulfide from natural gas

Examples

Experimental program
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Effect test

example 1

Synthesis of 2-methoxyethyl-N-methyl-ethanolamine (MDEA-OMe)

[0098]

[0099]The secondary amine 2-N-methylaminoethanol (3.76 g, 0.05 mol), N,N-diisopropylethylamine (DIPEA) (6.46 g, 0.075 mol), 2-methoxyethyl bromide (7.30 g, 0.0525 mol) and 30 mL acetonitrile were placed in a round bottom flask and stirred at room temperature under nitrogen. After completion of the reaction, (˜6 h, monitored by HPLC) the reaction mixture was evaporated under reduced pressure in a rotary evaporator. The residue was dissolved in 50 mL of dichloromethane and washed with 50 mL of 50% sodium hydroxide solution in water. The aqueous layer was washed with 3×15 mL portions of dichloromethane. The collected organic fractions were dried over sodium sulfate and the solvent was then removed under reduced pressure in a rotary evaporator at low 0-5° C. to yield the crude product finally purified by fractional vacuum distillation under sodium hydroxide to yield the product (1.6 g, 0.013 mol, b.p. ˜115° C., pressure i...

example 2

Synthesis of bis-(2-methoxyethyl)-N-methylamine (MDEA-(OMe)2)

[0101]

[0102]Bis(2-methoxyethyl)amine (35.45 g, 0.26 mol) was cooled to 0° C. in a 2-L round-bottom flask containing a stir bar. Following dropwise addition of 88% aqueous formic acid (47 mL, 0.91 mol), 37% aqueous formaldehyde (56 mL, 0.69 mol) was added. Controlled heating to 60° C. initiated rapid gas evolution. The reaction was allowed to proceed without further heating until gas evolution decreased (˜6 h) and was then heated to 80° C. for 24 h. The reaction mixture was cooled, acidified with 20% aqueous HCl, and extracted three times with 100 mL portions of diethyl ether. The aqueous layer was stirred in a salt / ice bath and brought to pH 12 by dropwise addition of 40% aqueous NaOH without allowing the internal temperature to exceed 25° C. Following separation of the resulting amine / aqueous layers, the aqueous layer was further extracted three times with 100 mL portions of diethyl ether. The combined organic layers were...

example 3

General procedures for 2-methyl-3-methoxy-2-propylamine (AP-OMe) and 2,2-dimethyl-3-methoxy-2-propylamine (AMP-OMe) syntheses

[0104]This Example demonstrates the synthesis of two alkoxy propylamine derivatives in a three stage synthesis in which the amino group on an initial propanolamine compound is first protected by p-methoxyphenyl protection (PMP-protection) to form a protected aminoalcohol which is then methylated on the hydroxyl group after which the protecting PMP group is removed to form the final methoxy substituted amine.

Step 1 p-Methoxyphenyl Protection (PMP-Protection)

[0105]A mixture of the selected amino alcohol (1 eq) and p-anisaldehyde (1.1 eq) was heated under reflux in benzene with azeotropic removal of water during 24 hours. The reaction was concentrated under reduced pressure. The desired products were recrystallized from hexane.

[0106]PMP-AP-OH, was collected as white microcrystals in a yield of 96%. 1H NMR (300 MHz, CDCl3) δ 8.09 (s, 1H), 7.53 (d, J=8.7 Hz, 2H), 6...

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Abstract

A process for increasing the selectivity of an alkanolamine absorption process for selectively removing hydrogen sulfide (H2S) from a gas mixture which also contains carbon dioxide (CO2) and possibly other acidic gases such as COS, HCN, CS2 and sulfur derivatives of C1 to C4 hydrocarbons, comprises contacting the gas mixture with a liquid absorbent which is a severely sterically hindered capped alkanolamine or more basic sterically hindered secondary and tertiary amine. The improvement in selectivity is achieved at the high(er) pressures, typically least about 10 bara at conditions nearing the H2S/CO2 equilibrium at which CO2 begins to displace absorbed hydrosulfide species from the absorbent solution.

Description

[0001]This application claims priority under 35 USC 120 from U.S. Application Ser. No. 61 / 859,325, filed 29 Jul. 2013.FIELD OF THE INVENTION[0002]This invention relates to a process for removing acid gases from natural gas and other gas streams at high pressure. In particular, it relates to a process for selectively removing hydrogen sulfide from these gas mixtures in the presence of carbon dioxide.BACKGROUND OF THE INVENTION[0003]A number of different technologies are available for removing acid gases such as carbon dioxide, hydrogen sulfide, carbonyl sulfide. These processes include, for example, chemical absorption (amine), physical absorption, cryogenic distillation (Ryan Holmes process), and membrane system separation. Of these, amine separation is a highly developed technology with a number of competing processes in hand using various amine sorbents such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), methyldiethanolamine (MDEA), diisopropylamine (DIPA)...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C10L3/10B01D53/14
CPCC10L3/103B01D53/1481B01D2252/204C10L2290/541B01D2252/20431B01D2252/20478B01D2252/20426B01D53/1468B01D53/1493B01D2257/304C10L2290/06C10L2290/12C10L2290/46Y02C20/40
Inventor KORTUNOV, PAVELSISKIN, MICHAELFEDICH, ROBERT B.
Owner EXXON RES & ENG CO
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